Journal Article

Conservative Decrease in Water Potential in Existing Leaves during New Leaf Expansion in Temperate and Tropical Evergreen <i>Quercus</i> Species

Takami Saito, B. Paul Naiola and Ichiro Terashima

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 100, issue 6, pages 1229-1238
Published in print November 2007 | ISSN: 0305-7364
Published online September 2007 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcm198
Conservative Decrease in Water Potential in Existing Leaves during New Leaf Expansion in Temperate and Tropical Evergreen Quercus Species

More Like This

Show all results sharing these subjects:

  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

Background and Aims

This study aimed at clarifying how the water potential gradient (ΔΨ) is maintained in the shoots of evergreen trees with expanding leaves, whose leaf water potentials at the turgor loss point (Ψtlp) are generally high.

Materials

The water relations were examined in current-year expanding (CEX) and 1-year-old (OLD) leaves on the same shoots in temperate (Osaka, Japan) and tropical (Bogor, Indonesia) areas. A temperate evergreen species, Quercus glauca growing in both sites, was compared with a temperate deciduous species, Q. serrata, in Osaka, and two tropical evergreen species, Q. gemelliflora and Q. subsericea, in Bogor.

Key Results

(1) In Osaka, the midday leaf water potential (Ψmidday) was slightly higher in OLD (−0·5 MPa) than in CEX leaves (−0·6 MPa), whereas Ψtlp was significantly lower in OLD (−2·9 MPa) than in CEX leaves (−1·0 MPa). In Bogor, Ψmidday was also higher in OLD leaves (−1·0 MPa) despite the low Ψtlp (−1·9 MPa), although stomatal conductance was not always low in OLD leaves. In the branch bearing CEX and OLD leaves, most of the hydraulic resistance (86 %) exists in the current-year branch, leading to differences in water supply between CEX and OLD leaves. The removal of buds just before breaking did not affect the high Ψmidday in OLD leaves after 1 month. Ψmidday in OLD leaves thus appears to be independent of that in CEX leaves.

Conclusions

The moderate decrease in Ψmidday in OLD leaves would contribute to maintenance of ΔΨ in the shoots during leaf expansion.

Keywords: Cohesion–tension theory; hydraulic resistance; leaf expansion; leaf water potential; pressure–volume curve; Quercus; turgor maintenance; water potential gradient

Journal Article.  7553 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.